Kildahl-Andersen Geir, Bruås Liv, Lutnaes Bjart Frode, Liaaen-Jensen Synnove
Department of Chemistry, Norwegian University of Science and Technology (NTNU), NO-7491, Trondheim, Norway.
Org Biomol Chem. 2004 Sep 7;2(17):2496-506. doi: 10.1039/B406913G. Epub 2004 Aug 10.
In the present study insight was gained on the larger complexity of cationic mixtures of diaryl (phi,phi-carotene, isorenieratene) and aliphatic (psi,psi-carotene, lycopene) carotenes, prepared by reaction with BF3-etherate, compared with beta,beta-carotene. Chemical reactions of the mono- and dications prepared in situ from the allylic carotenols beta,beta-caroten-4-ol (isocryptoxanthin) and beta,beta-carotene-4,4'-diol (isozeaxanthin), and from isorenieratene and lycopene were investigated using selected O, N and S nucleophiles; water, methanol, azide and thioacetate. In total 22, including 18 new, neutral carotenoid products were isolated and identified by VIS, MS and NMR (in part) spectroscopy. Their structures were compatible with the structures of the cationic intermediates. The formal addition of hydride to the various dications, required to rationalise minor reaction products, is discussed in terms of more likely hydrogen radical or proton transfer in cationic reactions. Extensive E/Z isomerisation was observed for all quenching products. The potential use of carotenoid cations for the synthesis of 4,(4')-substituted beta,beta-carotenes and 7-oxabicyclo[2,2,1]heptane derivatives is discussed.
在本研究中，与β,β-胡萝卜素相比，我们深入了解了通过与三氟化硼乙醚络合物反应制备的二芳基（φ,φ-胡萝卜素、异壬烯二酸）和脂肪族（ψ,ψ-胡萝卜素、番茄红素）类胡萝卜素阳离子混合物的更大复杂性。使用选定的O、N和S亲核试剂（水、甲醇、叠氮化物和硫代乙酸酯）研究了由烯丙基类胡萝卜醇β,β-胡萝卜素-4-醇（异隐黄质）和β,β-胡萝卜素-4,4'-二醇（异玉米黄质）以及异壬烯二酸和番茄红素原位制备的单阳离子和双阳离子的化学反应。总共分离并通过可见光谱、质谱和核磁共振（部分）光谱鉴定了22种中性类胡萝卜素产物，其中包括18种新产物。它们的结构与阳离子中间体的结构相符。就阳离子反应中更可能的氢自由基或质子转移而言，讨论了为合理化次要反应产物而向各种双阳离子正式添加氢化物的情况。观察到所有猝灭产物都有广泛的E/Z异构化。讨论了类胡萝卜素阳离子在合成4,(4')-取代的β,β-胡萝卜素和7-氧杂双环[2,2,1]庚烷衍生物方面的潜在用途。
